Understanding Opal Body Tone: What It Means and Why It Matters

At Iona Opal Australia, we’re often asked about the “body tone” of opals—and it’s one of the most important features to understand when choosing a stone. Body tone affects how colours appear in an opal and is a key factor in its value and visual impact.

What Is Body Tone?

Body tone refers to the base colour of the opal, independent of its flashes of colour (play-of-colour). It’s usually graded on a scale from N1 (black) to N9 (white), with crystal opals falling somewhere in between depending on their transparency.

Types of Body Tone

• Black Opals (N1–N4):
  These have a dark body tone and are often considered the most valuable. The dark background makes colours appear more vibrant and defined. Lightning Ridge is the world’s most famous source of black opals.

• Dark Opals (N5–N6):
  Slightly lighter than black opals, these still provide strong contrast for colour play but are often more affordable.

• Light or White Opals (N7–N9):
  With a milky or pale base tone, these are known for their soft, pastel-like colours. Coober Pedy is a well-known source for white opals.

• Crystal Opals:
  These opals have a transparent to semi-transparent body tone, allowing light to pass through and highlight inner colour layers.

• Boulder Opals:
  Cut with the natural ironstone backing intact, these opals often display body tones similar to black opals, with the added character of the earthy matrix.

Why Body Tone Matters

The body tone affects not only the appearance of the colours but also the opal’s rarity and value. Darker tones generally enhance contrast, making colour play more intense. That said, light opals and crystal opals have their own charm and are loved for their delicacy and glow.

Whether you’re after the drama of a black opal or the elegance of a crystal gem, understanding body tone will help you find the right opal for your style. Browse our range of solid Australian opals at Iona Opal Australia and choose with confidence.